A colleague of mine contacted me during the week to ask how one could
determine if a POWER7 system was capable of Active Memory Expansion. I thought
I'd share my response with everyone who follows my blog.

You can check if the system is capable of providing Active Memory
Expansion (AME), from the HMC command line using the lssyscfg command, as shown here:hscroot@hmc1:~>
lssyscfg -r sys -m Server-8233-E8B-SN1000 -F active_mem_expansion_capable1

Alternatively you can view the capabilities of
the managed system from the HMC GUI, under System properties/Capabilities, as
shown in the following image.

Once you’ve concluded that your POWER7 system is
AME capable, the next step is to check if AME is enabled or disabled for
an LPAR. This is easily done from the AIX command line with the lparstat and/or amepat commands, as shown in the following example:;Running
lparstat and amepat on a LPAR with AME
disabled.

Note
that I deliberately ran these commands as a non-root user to highlight the fact
that you don’t need root access to ascertain whether or not AME is active on an
LPAR.

By the
way, did you know that AME is now supported in SAP production environments running
on AIX and POWER7? Both SAP application servers, as well as database servers
running DB2 LUW are supported. Unfortunately there’s no support for LPARs with
Oracle RDBMS at this stage. Thanks to George Manousos from IBM Australia for
providing me with this update.

As AME is not
recommended with large page support, AME
will disable AIX

64KB pages by default.

AME monitoring
capability in CCMS

Monitoring
capabilities are available with saposcol v12.46 for more details see SAP note
710975.

It looks as
though SAP have been quick to support AME on AIX/POWER7. This is a great
benefit to SAP customers running with PowerVM on the IBM POWER platform. The
following screenshot shows the SAP CCMS with AME statistics being reported.

The SAP AIX porting team continues
in further improving the integration of PowerVM into SAP system monitoring. While
in the past already most processor and AIX virtualization metrics could be
monitored via CCMS, now POWER7 Active Memory Expansion (AME) has been
included. Customers will find a new memory section in the respective
CCMS-panel as depicted in this screen shot.

For those
who are not familiar with what AME actually is and how it can benefit you, I
suggest you take a look at the IBM AME Wiki site first:

If you are
a system administrator that is responsible for managing AIX systems that run
SAP, then you’ve probably had an experience similar to the following?

OK, so one
day my SAP Basis administrator contacts me and says “I can’t start saposcol......can
you please reboot the system?” I quickly reply, “Was there an error message when trying to restart saposcol?”. He
replies, “No”. Again I return very
quickly, “OK, have you checked to see if
there are any shared memory segments left for saposcol?”. Just as quick, he replies “How do I do that?”

Together
we try starting saposcol and what we
find is that it thinks it’s already running (as shown below, PID 327924). But there is no such process!

My
conclusion is that there must be a shared memory segment still allocated for
saposcol. There were many other SAP processes still running happily, so there
were several shared memory segments to sift through. So, what shared memory ID
does saposcol use?

Now, according
to the following website, shared memory key 4dbe is used by saposcol on AIX.

Answer: Sometimes it may be
necessary to remove the shared memory key of saposcol (see point 6). Caution:
Please be very careful! This procedure should be performed only after checking
that saposcol is really not running (see point 4) and only in cases when other
options (see point 6) really do not work! For this, execute command “ipcs -ma”
and note the line that contains saposcol key “4dbe”. You need the shared
memory ID. After that, execute command ipcrm -m ID. Now the command “saposcol
-s” should show that saposcol is not running and that the shared memory is not
attached. The shared memory key will be created automatically by the saposcol when
the collector is next started: “saposcol -l”.

So I run ipcs to check for the existence of 4dbe. And I find an entry for this key.

There are
several process id’s ‘attached’ to this segment. However, only one of them actually
exists (PID 2293794).